Electro-pneumatic control systems are increasingly being employed with process control devices, such as valve actuators and piston actuators, in order to provide better or more optimal control of fluid within a process plant. Some such electro-pneumatic control systems include one or more accessories for controlling valve and piston actuators such as volume boosters and quick exhaust valves (QEVs). A volume booster, which is typically coupled to a pneumatic actuator for a valve, increases the rate of air supplied to the pneumatic actuator, or increases the rate of air exhausted from the pneumatic actuator. This increased air movement amplifies the actuator stroke speed, thereby increasing the speed at which the actuator is able to stroke the valve plug toward its open or closed position, and thus enables the valve to respond more quickly to process fluctuations. Similar to volume boosters, QEVs increase the speed at which an actuator is able to stroke a valve toward an open or closed position.
Currently, volume boosters are utilized with pneumatic actuators in a manner that makes the actuators move very slowly in response to very small set point or control signal changes. In particular, some volume boosters are designed with a built-in dead band to actually prevent the volume booster from becoming active in response to small amplitude change control signals. While some volume boosters have small dead bands at the lower amplitude signal range, these volume boosters still move very slowly in response to small amplitude signal changes, becoming fast only in response to larger amplitude input signals.